Once, on his way south in chains, Esca saw a white horse carved into a hillside. Six years later, on their way to visit Cottia's mother, Cottia and Esca see the White Horse of Lubrinium, and Cottia tells Esca a story of the Iceni, long ago, before the Romans came to Britain. Sort of an Eagle of the Ninth/Sun Horse, Moon Horse crossover, bookverse.